Selective sediment discharge valve for an emulsion treater



R. W. ERWIN Sept. 8, 1959 SELECTIVE SEDIMENT DISCHARGE VALVE FOR ANEMULSION TREATER OriginalFiled July 12, 1955 5 Sheets-Sheet 1 ww lHQIWHES 1 I H1 1 .zwi N INVENTOR ATTORNEY R. w. ERWIN Sept. 8, 1959 3Sheets-Sheet 2 Original Filed July 12, 1955 INVENTOR R. w. ERWlN Sept.8, 1959 SELECTIVE SEDIMENT DISCHARGE VALVE FOR AN EMULSION TREATEROriginal Filed July 12, 1955 3 Sheets-Sheet s INVENTOR m EMULSION-ATTORNEY 2,903,015 1C6 Patented Sept. 8, 1959 SELECTIVE SEDIMENTDISCHARGE VALVE FOR AN EMULSION TREATER Ransome W. Erwin, Fort Worth,Tex., assignor to Salt lrgalt er Control, Inc., Fort Worth, Tex., acorporation exas Original application July 12, 1955, Serial No. 521,553,now Patent No. 2,868,312, dated January 13, 1959. Divided and thisapplication February 19, 1957, Serial No. 644,962

5 Claims. (Cl. 137546) The invention relates primarily to improvementsin emulsion treaters of the general type disclosed in my Patents Nos.2,601,903 and 2,601,904, dated July 1, 1952, although some of theindividual features of the present invention are capable of broaderapplication.

In accordance with the disclosure of my prior patents referred to abovean oil and water emulsion under pressure and containing gaseousconstituents is subjected to heating, settling, baffling and filteringoperations in order to separate the water from the oil and gaseousportions of the emulsion, the water being withdrawn from the treaterseparately from the oil and gas. The emulsion may be derived from aflowing oil well or other source.

The emulsion treaters of my prior patents are of the horizontal type andeach includes a removable heating unit comprising a plurality ofinterconnected tubular elements heated by gas burners or the like, theheating unit being located at one end of the treating casing, to whichheating unit the emulsion entering the treater is subjected to initiallyseparate the gas, oil and water into separate layers, following whicheach layer is subjected to settling and/ or filtering treatments toeffect more complete separation, after which the oil and gas and waterare removed from the discharge end of the treater remote from the heaterand the hot oil leaving the treater is cooled by heat interchange withthe entering emulsion by means of a suitable heat interchangersurrounding the emulsion inlet end of the treater.

The construction herein shown follows the same general arrangement as myprior patents, but includes among other features (a) improvements in theheat interchange construction and arrangement, (b) improvements in theoil and water heating unit or tubular elements thereof, and (0) improvedmeans for removing sediment from the bottom of the treater, which meansmay be referred to as a selective sediment bleeder. These features willfirst be generally discussed in order and with advantages pointed out,and will then be illustrated in their application to a specifichorizontal oil treater.

Feature (a) referred to above is claimed in my application Serial No.521,553, filed July 12, 1955, and now Patent Number 2,868,312, feature(b) is claimed in my application Serial No. 644,961, filed February 19,1957, while feature (0) is the subject matter of the presentapplication.

More specifically, the invention of the present application is directedto selective sediment discharge valve means for an emulsion treatercomprising a flexible belt overlying a perforated bottom portion of thetreater, and means for selectively raising portions of the belt toprovide mechanical agitation of the sediment accumulated therein, and topermit said sediment to flow outwardly through selected openings in thebottom of the treater.

Heat interchange arrangement In accordance with feature (a) the heatinterchanger is applied to the upper part only of the inlet end of thetreater so as to more effectively utilize the heat from the heating unitwhich is located in the portion of the inlet.

end, and also to leave the bottom of the treater readily accessible forremoval of sediment. The hot clean oil and gas from the discharge end ofthe treater are passed to one side of the outer portion of the heatinterchanger and are caused to pass back and forth lengthwise of theheat interchanger by means of suitable baffles or spacers before finallyleaving the heat interchanger from the op,- posite side from which theoil and gas enter such heat interchanger, having in the meantime beencooled by heat interchange with the entering oil and water emulsion.Such emulsion enters an inner metal jacket contacting the oil jacket onthe outside and hot water and oil layers on the inside, and passes in azig zag arrangement in countercurent relation to the oil and water inletuntil it finally enters an emulsion zone in the treater below theheating zone thereof. In this manner full use is made of the heat of theclean outgoing gas and oil, and by reason of the fact that gas isincluded with the oil the heating zone is insulated so that no heat iswasted.

Oil and water heating unit comprising coated tubular elements Thisimprovement in heating elements for heating and treating mixtures of oiland water, especially mixtures of crude petroleum and mineral-containingformation waters,

steel wall of the heating element directly to the oil-waterv mixtureitself. Common practice is to immerse the heat ing element in the waterlayer or zone of the heating vessel, heat the Water itself, and transmitthe heat to the oil by passing the oil upward in streamlets through thebody of the heater water. Some treating methods, including those shownin my Patents Nos. 2,261,101, 2,601,- 903 and 2,601,904, emphasize adirect washing of the water immersed heating element with these oilstreamlets in order to give more direct heating of the oil itself and inorder to lubricate the heating element surface to minimize mineral scaleformation. This method has proved to be beneficial in some cases, butonly partially so where scale prevention is concerned. It is well knownthat an insoluble calcium carbonate is formed by heat breakdown ofsoluble calcium bicarbonates usually contained in earth formationwaters. Most steel or metallic surfaces are by nature hydrophilic orpreferentially water wettable, unless treated to be otherwise; hence asteel or metallic heating element submersed in water will contain waterfilms on its surfaces even though oil streams are passing by it. If notviolently disturbed these water films become superheated above thetemperature of the water body, forming calcium carbonate precipitateswhich form and grow on the heating element surface. This coating ofcalcium carbonate acts as an absorbent to detain or retain more waterwhich, in turn is overheated, forming still more precipitates. The finalresults, if the deposit is not removed mechanically, are insulation ofthe heating element, overfiring, and final burnout of the heatingelement.

I have found that treating the liquid exposed surface of a heatingelement to render it preferentially oil wettable, in combination with anoil wash while submersed in a water bath or medium, not only preventsformation of mineral scale accumulations on the heating element surface,but actually prevents the usual mineral precipita tion itself. Thisrendering preferentially oil wettable of the heating element surfaceexposed to oil and water may be accomplished in several conventionalways. It may be treated by coating with any of several siliconecompounds, well known in the art of oil wetting or waterproofing, thatare permanent, stable, and heat cured to render them less susceptible totemperatures up to the boiling temperatures involved treating oil andwater mixtures, such ternperatures being sometimes as high as 250 to 300F. Another very successful method of treatment, one which also protectsthe metallic heating element from chemical and electrolytic corrosion,is to sand blast the metal surface clean, coat with several thin coatsof a suitable thermosetting plastic such as epoxy or phenol formaldehyderesins, and oven bake the resin at 400 F. Details of the resin coatingand baking operation are unnecessary here as this is a standard practicewell known in the industry. Any suitable method for applying a coatingmay be employed as, for example, by dipping, spraying, brushing or thelike, followed by a baking operation to set the plastic coating, as iswell known to those skilled in the art.

Test results-A pipe type tri-tube heating element as described in myPatents Nos. 2,495,673; 2,601,903 and 2,601 ,904 was coated with a highbake phenolic forma1dehyde resin. This element was inserted into thechamber, which also was coated with a phenolic formaldehyde resin, of ahorizontal emulsion treater generally similar to that described in myPatent No. 2,601,904. This treater was tested in an oil field whichproduces oil and much brine, and which contains so much soluble calciumbicarbonate that the treater had to be opened and cleared of lime scaledeposits every three or four months. The scale would form on the heatingelement, build up, slough off and pile up beneath the element. Manyanti-scaling remedies were tried, such as chemical treatment of thebrine and magnesium anodic treatments, but with no appreciable success.Only expensive shut-down, removal of heating element and manual cleanoutof scale every three or four months would permit continued operation.Subsequently the treater was put in line with the plastic treatedfirebox and heating chamber. After four months operation it was notedthat the treater was heating the oil and water as'easily as at first,indicating non-scaling of the heating element. After six monthsoperation it was opened and inspected. There was no scale on the heatingelement (it was clean and oily), the plastic coating seemed quiteintact, and even more significant, there was no calcium carbonate scaleor sediment on the floor beneath the heating'element. Obviously, theprecipitates were not forming. It was interesting to note, however, thatscale approximately /4 thick had formed on that portion of the plasticcoated interior of the heating-wash chamber'which received no oilwashing. This scale was not tight, and came loose with little mechanicaleffort. It was co ncluded that the plastic discouraged adhesion of thescalesbut did not prevent its formation where there was no oil washingto keep the surfaces oil wet as is done by design of the heating elementitself. Finally it was concluded that the combination of oil wettablesurface, submersed in water, subjected to washing by oil is the key tomineral scale or precipitate prevention in oilwater mixture heating.This test treater was inspected at intervals with the same findings eachtime. of the test it was safely concluded that this method of treatmentwas highly satisfactory, and that the plastic treatment was economicaleven if it should require recoating at infrequent intervals.

Among the objects of this phase of the invention are: (1) To preventformation of insoluble mineral scale and precipitates due to overheatingwater films in heat treating oil-water mixtures.

(2) To minimize chemical and electrolytic corrosion of exposed surfacesin oil-water mixture heat treating systems by rendering surfacespermanently oil wettable and Washing same with insulating coat of oil. IV Y At the end (3) To provide more efficient transfer of heat directlyto oil being heated in oil-water mixture heat treating systems byelimination of mineral scale deposits on the heating element and keepingthe element wet with oil, though immersed in water.

.(4) To prevent burn-out of the heating elements.

(5) To heat oil and water more etficiently with less B.t.u. consumption.

(6) To minimize costly shutdown and cleanout of oilwa c t eating syst m.

(7) To protect the heating element from costly electrolytic and chemicalcorrosion.

Sediment removing meansselective sediment bleeder for horizontalemulsion treater The third general feature of my invention covered bythe claims of the present application relates to the removal of thesediment which tends to collect at the bottom of the horizontal treater,particularly in the heating and settling zones of which zones maytogether be considered as a sediment settling zone or area within thescope of the present invention, since sediment falls by gravity to thebottom of the tank within this portion of the treater. Such treater,such sediment removal is accomplished according to my invention by theuse of what I choose to term a selective sediment agitator and bleederwhich is especially adapted for use with an emulsion treater of thehorizontal type.

The use of horizontal, cylindrical vessels or tanks for handling fluidssubject to sediment fall-out has always been hampered by the diificultyof bleeding or draining such sediment from the vessel, which is a muchmore difiie cult problem than that which is involved where using avertical vessel with a coned or dished bottom. It is obvious that in avertically disposed vessel the sediment falls into the bottom cone whereit may be bled off through an opening usually in the center of thebottom. In a hori zontally disposed cylindrical vessel the sedimentusually drops out throughout the length of the vessel. To drain suchsediment there are usually multiple drain openings and valves located atclose intervals throughout the length of the vessel. This, of course, isquite expensive and still not adequate, as only a small spot is drainedclean. If some sort of perforated drain or pick-up pipe is used this issubject to becoming clogged and unworkable. Other recourses in suchinstances are violent agitation in the vicinity being drained; orshutdown of process, drainage of vessel and manual clean-out. The dropout of mud and sand, for example, in horizontal emulsion treaters, andthe expense and difiiculty of removing the same, have tended to someextent to off-set the many advantages that these' horizontal treatershave over vertical ones. Thus, to fully realize all the many benefits tobe derived from horizontal treating and settling processes I haveprovided beneath the longitudinal center of the treater a sediment andsand receiving channel or trough having an outlet pipe leading therefromto a sand pit or the like, communication between the treater tank andthe i trough being provided by means of aligned apertures in 60 thebottom of the tank, which are normally covered by a longitudinallyextending flexible belt of suitable rubberlike material such asneoprene, portionsof which belt above the aperture are adapted to beselectively opened by manual means accessible from the exterior of thetank. Thus, in effect, the belt and operating means therefor constituteselectively operating valve mechanisms for draining sediment from thebottom of the tank. This arrangement has the following advantages, amongothers:

(1) As contrasted. to agitation of sediment by gas, especially inemulsion treating which disturbs the whole treating and settlingprocess, this method permits mechanical agitation of sediment forbleeding off while the treating eqipment is in full use.

(2) The equipment operator can bleed off the sediment with ease and in aminimum of time.

(3) The bleed-01f arrangement is rugged, simple and foolproof.

(4) It provides selective full valve drainage for all parts of thevessel bottom, using only one drain line valve.

(5) The first cost of the sediment bleeder is not excessive compared toother bleeding methods commonly employed, and the savings in time andlabor for general manual clean-out very quickly will pay out this firstcost.

The invention will be more readily understood by reference to theaccompanying drawing and the following detailed description, in which ahorizontal emulsion treater embodying the various features of myinvention is shown by way of illustration rather than by way oflimitation.

In the drawings:

, Fig. 1 is a vertical longitudinal section through my improved treater,parts being broken away and others being shown in elevation;

Fig. 2 is a top plan view of the jacketed heating end of my heater on alarger scale than Fig. 1, part of the outer jacket being broken away toshow the battles;

Fig. 3 is a vertical transverse section on line 3-3 of Fig. 1 and on alarger scale than Fig. 1;

Fig. 4 is a detail longitudinal section on an enlarged scale showing aportion of the sediment trough and a selective sediment bleederarrangement used in connec tion therewith.

The apparatus as a whole and its mode of operationare generally similarto what is disclosed in my prior Patents Nos. 2,601,903 and 2,601,904,particularly the former, and accordingly only -a brief description ofits general construction and operation will be necessary, referencebeing had to said prior patents for a further understanding thereof.

As shown, the treater comprises an elongated horizontal tank mounted onskids or the like 211 so as to permit it to be moved from place toplace. The tank 10, Which constitutes the main treating vessel, isdivided lengthwise into four main zones designated from right to left asthe entering and heating zone A, the settling zone B, the filtering zoneC, and the discharge zone D, through which zones the fluids undergoingtreatment are passed successively from their entry into the system totheir removal therefrom, it being understood, however, that hot oil andgas leaving the treater and the cold emulsion entering the system arepassed in heat interchange relation through a heat exchanger E locatedat that part of the zone A in which the heating unit 13 is located.

The entering and heating zone A is sub-divided into an upper or heatingzone A, and a lower zone or chamber A by means of a partition 14 morefully described in my Patent No. 2,601,903. Separation of free waterfrom the emulsion takes place in the zone A and two distinct layers areformed, the lower layer being free water and the upper layer below thepartition 14 being emulsion.

The entering zone A is divided from the settling zone B by means of apartition 15 which terminates short of the bottom of the tank so as toprovide access between the water layer at the bottom of the zone A andthe water layer in zone B. The partition 15 is provided with an upperopening 16 and a spreader box 17 permitting passage of hot oil from zoneA to zone B. Apertures 17*" are also provided above the opening 16 tointerconnect the gas layers in the top portions of zones A and B. Thefiltering zone C is separated from zones B and D by means of perforatedwalls 19 and 20 which serve to retain filtering materials 21 such asglass fiber, excelsior or the like. No sediment is permitted to passbeyond the zone B. From the discharge zone D, which is also a settlingzone, water is drained off through outlet pipe 21 and water legs 22, 23to discharge pipe 24 having a diaphragm dump valve 25 therein controlledby gas equalizer pipe 26, which pipe connects with gas equalizer pipe27, which in turn connects the gas zone at the top of the tank 6 V withthe interconnecting portion 28 between the tops of the water legs.

From the upper portion of the discharge zone D hot clean oil and gas arewithdrawn through an overflow outlet 29 and down pipe 30 which emergesfrom the side of the tank at 31 and passes externally along the line 32until it enters the outer jacket of the heat interchanger E at 34 andflows in a zigzag path back and forth lengthwise of the tank by reasonof a series of spaced baffle plates 35, until the stream of now cooledoil and gas emerges from the treater at 36 and is passed to a suitableplace of storage (not shown).

The heat interchanger As shown, the heat interchanger E comprises innerand outer jacket portions 40 and 41 extending about the heating zone Aand terminating approximately at the lower water knock-out Zone A Theouter jacket 41 receives the outgoing oil and gas, as previouslydescribed, and the inner jacket 40 receives the incoming emulsion whichenters the jacket under pressure at 42, and after a zigzag passage backand forth lengthwise of the jacket by reason of bames 43 similar to theouter baffles 35 enters the lower water knock-out zone A at 44, beingguided thereto by an extension 45 of the inner wall of jacket 40. Thearrangement of baflies 35 and 43 is best shown in Fig. 2.

In the knock-out chamber A free water separates out from the emulsionand sinks to the bottom to form layer W in the bottom of zone A whichlayer communicates with water in the bottom zone B through the openingbeneath partition 15 as previously described, and from this combinedwater zone sediment may be removed by the aid of my selective bleederarrangement F at the bottom of the tank, which will be more fullydescribed hereinafter.

The preheated emulsion from the heat inter-changer E entering thetreater at 44 forms an upper layer in the zone A above the water layerW, and passes upwardly through pipes 50 extending through partition 14and thus through Spreaders 51 into the upper zone A of the treater, andthen the emulsion passes upwardly around the two lower fire tubeelements of the heater unit 13, as best indicated in dotted lines inFig. 3, thereby caus ing separation of the emulsion into its water, oiland gas components, the water collecting in a lower layer, the gas in asmall upper layer, and the oil collecting in the intermediate layersurrounding the uppermost fire tube of the heating unit. Thus it will beapparent that the three elements of the heater unit are at all timessurrounded either by the upwardly flowing emulsion which contains an oilcomponent and which contacts the two lower elements, or by therelatively clean oil in the upper portion of the zone A as in the caseof the uppermost tubular element of the heater.

The heater unit In accordance with my invention as previously set forththe fire tubes of the heater unit are pretreated by coating on theliquid side with a suitable coating which renders them preferentiallyoil wettable instead of water wettable, thereby protecting them fromchemical and electrolytic corrosion, and to a large extent preventingthe formation of hard carbonate scale. The coating may be of siliconecompounds, phenolic or epoxy resins, or other suitable thermosettingplastic material. Thus the oil constituent of the emulsion rather thanthe water wets the two lowermost fire tubes although such tubes areactually located in the water or brine layer. The uppermost tube islocated in the oil area, though some water may remain in such area, butsince the uppermost tube is likewise preferentially oil coated corrosionand scale formation are largely prevented.

As previously described, the clean oil passes from the zone A into zoneB through the opening 16 and thencethrough filter chamber C into asecond settling or discharge chamber or zone D. The gas likewise followsa similar path above the oil layer.

Sediment removal I have found in practice that large quantities ofsediment, sand or the like tend to accumulate in the lower portion ofzones A and B, zones C and D being largely free from sediment owing tothe presence of the screens and filtering material in zone C and also tothe fact that settling has largely been completed in the first two zonesA and B. For this purpose I have provided what I chose to call aselective sediment bleeder F extending along the longitudinal center ofthe bottom of zones A and B. As shown the bottom of the tank in thesezones is provided with spaced perforations or openings 60, and beneaththe perforations there is provided a trough or channel 6 1 U-shaped incross section and having an oiftake pipe 63 leading from the bottom, ofvalve 63 thereof to a disposal pit or the like (not shown). Within thetank a flexible belt 64 is provided which normally covers the aperturesand which is preferably composed of neoprene or other suitablechemically resistant rubber-like material. A plurality of means, eachgen erally designated by reference numeral 65, serve to selectivelyraise portions of the belt at the desired locations to permitaccumulated sand, sediment and the like to pass from the bottom of thetreater through one or more openings 60 into the trough 61, thencethrough valve 63' (which has been opened) and through drain pipe 63 tothe disposal pit. The belt thus serves as a selectively operable valve.One such belt lifting or valve operating mechanism will be described asillustrative.

As shown the belt lifting or valve actuating means 65 comprises areciprocable rod 66 passing through stuffing box 66 and then through thetrough and connected at its upper end to the belt by means of nuts 67,68 and pivoted at its lower end at 69 to an operating lever 70 adaptedto be raised or lowered to effect raising or lowering of a portion of abelt 64. When a portion of the belt is thus raised sediment or the likemay pass through one or more apertures into the trough below. When thebelt is lowered the openings are closed. As will be apparent, theraising of the belt results in mechanical agitation of the sedimentsince the sediment is thereby forced to the edges of the belt and thenfalls off the edges and is washed through the adjacent opening by thewater in the immediate vicinity. Thus selective bleeding of the entirebottom portion of zones A and B of the tank is made possible and thetreater may be operated for long periods of time without shutting downfor cleaning purposes. Similarly, the treatment of the tube elements ofthe heater unit 13 with an oil wettable coating increases the life ofthe heater unit which otherwise would have to be removed or replaced atrelatively frequent intervals owing to the high temperature maintainedtherein by reason of the fact that hot gases flow therethrough from oneor more burners 100 as set forth in my Patents Nos. 2,495,673, 2,601,902and 2,601,904.

As previously stated the general. operation of the treater is much thesame as that described in my Patent No. 2,601,903, the emulsion beingintroduced into the system under pressure and pressure being equalizedthroughout the system by gas equalizer pipes, the gas being withdrawnalong with the clean oil and passed in countercurrent to the incomingemulsion in the preheater E. By reason of the fact that the preheater isconfined to the upper zone A and does not extend to the lower zone A thebleeder F may be readily employed at both zones A and B where fall outof sediment is most prevalent. It will be further noted that thepresence of gas in the outgoing fluid passing through the outer jacketof the heat exchanger E increases the insulating capacity of the heatexchanger so that relatively little heat is lost to the outside, anouter layer of gas being provided adjacent the outer wall of the treatertank in zone A. a

The invention has been described in detail for the purpose ofillustration but it will be obvious that numerous I modifications andvariations may be resorted to without departing from the spirit of myinvention within 'the scope of the accompanying claims.

I claim:

1. A horizontal emulsion treater comprising a tubular tank having asediment separating zone extending lengthwise thereof wherein sedimentis separated from an emulsion and falls by gravity to the bottom of saidtank, said bottom having perforations therein, and means comprising anelongated flexible sediment bleeder overlying the perforated bottomportion for simultaneously agitating the sediment and providing for thedischarge thereof through selected ones of said perforations.

2. An emulsion treater comprising a horizontally disposed tank having asediment separating zone disposed lengthwise thereof wherein sediment isseparated from an emulsion and falls by gravity to the bottom of thetank, said bottom having 'a series of longitudinally disposedperforations, and a selective sediment bleeder comprising a flatflexible belt overlying the perforated bottom portion of the treater,and means for selectively raising portions of the belt to providemechanical agitation of the sediment accumulated therein and to providefor the discharge. thereof through selected ones of said perforations.

3. An emulsion treater as set forth in claim 2, wherein a trough isprovided beneath the perforated portion of the treater to receive andconvey sediment from the treater when a portion of the belt is raised.

4. An emulsion treater comprising a horizontally disposed tank having asediment separating zone disposed lengthwise thereof wherein sediment isseparated from an emulsion and falls by gravity to the bottom of thetank, said bottom having a series of longitudinally disposedperforations, and a selective sediment bleeder comprising a fiatflexible belt overlying the perforated bottom portion of the treater,and manual means accessible beneath the tank for selectively raisingportions of the belt to provide mechanical agitation of the sedimentaccumulated therein and to provide for the discharge thereof throughselected ones of said perforations.

5. An emulsion treater as set forth in claim 4, wherein the manual meansare attached to the belt at successive intervals adjacent successiveperforations.

References Cited in the file of this patent UNITED STATES PATENTS597,954 Cartwright Jan. 25, 1898 766,420 Calley Aug. 2, 1904 2,510,252Pine June 6, 1950 2,548,333 Anderson Apr. 10, 1951 2,731,802 MacSporranJan. 24, 1956 2,768,639 Stillwell Oct. 30, 1956 2,781,780 Zahradk-a Feb.19, 1957 2,786,643 Carlstedt Mar. 26, 1957

